Misguided Debates about Human Sexuality

Are men shaped by evolution to be more inclined toward casual sex? Or is it simply a function of how people are socialized? This recent variant of psychology’s (in)famous nature-nurture debate is the topic of an Op Ed piece in today’s NY Times. In the article, Darwin Was Wrong about Dating, the author Dan Slater notes that evolutionary psychologists have been developing Darwinian frames explaining why women are the choosier sex for the past forty years. Except now, he writes, “over the past decade, sociocultural explanations have gained steam”. He goes on to cite several studies where the findings suggest maybe much of the gender differences in sexual behavior are contextually based. From this he concludes that the evolutionary psychological explanations are threatened, writing, “The fact that some gender differences can be manipulated, if not eliminated, by controlling for cultural norms suggests that the explanatory power of evolution can’t sustain itself when applied to mating behavior.”

From the unified psychological perspective, this debate between sociocultural and evolutionary psychologists on the cause of our behavior is grossly misguided. Our position is that both sides have limited frameworks that fail to incorporate the key insights of the other side, and this, in turn, leads to straw man claims about what the other side says, resulting in lame debates and breakdowns in communication. Here are a couple of key principles to keep in mind from getting sucked in to this debate in a bad way.

1. Everyone agrees that the nervous system is a plastic system that acquires behaviors in context, and that no complex human behaviors (like dating) are reducible to evolved instincts in the “fixed action pattern” sense of the word. Many social scientists, like Slater, create the straw man that evolutionary explanations mean such behaviors “take on the immutability of a physical trait – they come to seem as biologically rooted as opposable thumbs or ejaculation”. This is a ridiculous claim. Any sophisticated evolutionary psychological argument takes the form of a “learning preparedness” argument, meaning that evolution predisposes individuals to have certain inclinations toward values, reinforcement and goals and that they will, all things being equal, tend to learn certain patterns over others.

2. Evolutionary psychologists are often guilty of storytelling. Evolutionary psychologists too frequently engage in the pattern Slater points out, which is that they start with a possible observation of current human behavior (say, for example, males seem to be more jealous of females sexual infidelity), then they develop some possible evolutionary explanation (female infidelity was more threatening to inclusive fitness than male infidelity), then they develop some novel experiment to test whether males are more jealous than females, and, upon finding that, argue the evolutionary explanation was supported. This is BS. The only thing that was supported was the original observation. To actually directly support the claim, one would need to go back in time and measure the jealousness of various males and females and see if that tendency influenced reproductive success. Of course, that is essentially impossible to do.

3. Evolutionary psychologists have not been effective in spelling out the learning preparedness argument. In many ways, evolutionary psychology got defined against behavioral learning theories and socialization theories, resulting in unnecessary fragmentation. Critics like Slater get away with the straw man instinct portrayal because evolutionary psychologists have not attended or explicated clearly how the nervous system is a learning preparedness system. Instead, because old learning perspectives emphasized general learning patterns, evolutionary psychologists tended to be defined against the behaviorists. This is a mistake. A part of the unified theory, Behavioral Investment Theory, explicitly articulates how evolution can be blended with learning theory.

Let’s return to the topic at hand, differences between men and women in their tendencies to engage in casual sex. The way the unified theory frames the issue is to first determine the evolutionary logic. Is there a good evolutionary logic that males and females would be prepared to invest differently in casual sex? The answer here is absolutely yes. Why? As Slater mentions, Trivers’ Parental Investment Theory provides a clear answer. In terms of “genetic payoff” (i.e., genes in the next generation), an offspring is of equal value to the mother and the father. However, in terms of investment for that payoff, in the case of casual sex, it is clear that the woman will “pay” much more in terms of risk, calories, action effort, and so forth. From this very basic perspective, we can say that, all things being equal, the male gets the significantly better deal. This makes a very clear prediction about how males and females IN GENERAL (i.e., at the population level) will view casual sex. For example, since humans have invented money as a symbol of human investment, we can ask the basic question, which sex would be more likely, given the above set up, to pay the other for sex? Parental Investment Theory is very clear. It predicts males will be much more likely to pay females for sex than the reverse. Now look around and see what cultures have money and see if that trend holds as a general pattern. Surprise, surprise, males tend to pay females for casual sex across virtually every culture examined.

This is the proper way to understand evolutionary forces. But you must also understand that these forces are “distal” and that they are mediated via learning (experienced patterns of investment over the course of the individual’s lifetime) and socialization (the shared beliefs and values of what are legitimate). If you have this perspective, it will not surprise you at all to learn that many men will be very reticent to engage in casual sex, either out of experiences or internalized justification systems that they were socialized in, and that the reverse will be true for many woman.

Armed with the right understanding of evolution, investment and justification, we can move past the old nature-nurture dichotomies and toward a much more sophisticated view of the human condition.

Greg -- I fully agree with your nature/nurture argument. With regard to your theory itself, although I find the general framework very useful,I have a problem with your idea that the evolution of human culture was based on the need of humans to justify their behavior.

Whenever language evolved, it would have provided the hominins with adaptive advantages not possessed by their ancestors. For example, the ability to label objects and actions would have allowed them to coordinate their behavior in ways that were not possible for earlier-evolved species. Their ability to create and share narratives about survival-relevant experiences would have formed the basis of a cultural heritage that could be passed down intergenerationally.

The richness of these benefits seem lost in your self justification hypothesis. I find it hard to imagine that something so specific would be the 'prime mover' for evolutionary change.

Hi Nancy,
Thanks much for your comment, and I appreciate your point. In that, let me state clearly that the JH takes the evolution of at least a basic human symbolic-syntactical language as a starting point. And I totally agree that the emergence of language was a great and beneficial adaptation that undoubtedly resulted in a bunch of cognitive and social changes. So, for the record, I am not at all denying your point.
But my point is the additional question, "So how does human language, self-consciousness, human reasoning capacities and the organization of cultural narratives become functionally organized?" My answer to that question is that human self-consciousness and human cultural knowledge can very usefully be characterized as "justification systems". That is, our linguistic, declarative knowledge systems are organized into functional networks (narratives) that legitimize claims and actions--i.e., they are reason giving networks. Moreover, our self-consciousness system looks to me as though it was designed to be a social reason giving system. Kids learn to reason about the social environment and offer sophisticated justifications to their parents long before they are able to engage in formal, asocial, analytic reasoning.
As I often remind the evolutionary psychologists, it is very hard to go back in time and determine what was selected for. Thus, in someways, like most evolutionary ideas, the JH is speculative. And, the question as to what extent the adaptive problem of social justification was "THE" prime mover or a prime mover or one of a multitude of factors is hard to say. Nonetheless, the value in the idea, for me at least, is that our human world becomes much more readily comprehensible at both the individual and macro-social levels if we think about human self-consciousness as being shaped by evolution to be a social reason giving system and if we think about the organization of our knowledge about ourselves and worldviews in general as systems of justification. It was, in fact, understanding human linguistic knowledge systems as systems of justification that was the key insight that I had in 1996 that led to the rest of the system I have built.
Best,
Gregg

I'm sensitive to your concern about "cultural benefits" and "the richness of these benefits," but (of course "but") don't see how the Justification Hypothesis is "something so specific."

It seems to me that the JH is a very general way of addressing the fact that cultural structures emerge from and are thus informed by pre-existing animal concerns / Behavioral Investment Theory--we are, after all, "the third chimpanzee." In other words, human culture (from clothing to cathedrals) involves the sublimation of human animality and fundamentally the fear of death (as discussed by Ernst Becker in *The Denial Of Death*).

Personal neuroses and psychoses involve similar but dysfunctional sublimations , and are likewise usually unconscious.

In any case, I don't think it detracts from the beauty / richness of a sonnet to recognize that poetry likely originated as a means of seduction / sexual justification.